The present invention relates to network communications. More particularly the present invention relates to self-organizing wireless networks applying a logical neighborhooding technique to adjust to the network density.
Mobile multi-hop broadcast packet radio networks are known for their rapid and convenient deployment, self organization, mobility, and survivability. In this type of network as illustrated in FIG. 2, a transmission from one node, for example node 1, is broadcast to all nodes in its xe2x80x9cneighborhoodxe2x80x9d. Ultra-high frequency (UHF) systems generally have a neighborhood defined by nodes within line of sight of the transmitting node (these nodes being termed within one xe2x80x9chopxe2x80x9d of the transmitting node). For example, in FIG. 2 nodes 1, 3, 4, 5, 6, 7, and 8 make up one neighborhood. For data transmitted from node 1 to propagate multiple hops, the data must be relayed by one or more of node 1""s neighbors. For example, node xe2x80x9caxe2x80x9d (likewise nodes b, c, and g) is two hops away from the node 1 transmitter. The data will be relayed in this manner until it has arrived at all intended destination nodes.
Since there are generally limitations on the number of simultaneous transmissions that a receiver can successfully process (typically one), collisions can be avoided by the assignment of time slots in which individual nodes can transmit. There are many approaches to deciding which nodes are assigned which slots, and the approach is generally driven by the network applications, such as, broadcast, multicast, unicast, datagrams, virtual circuits, etc. Because the problem of optimally assigning slots in this environment is mathematically intractable, a heuristic approach is taken to design an integrated protocol that both chooses the number of slots to assign to each neighboring node and coordinates their activation in the network.
Tactical military and commercial applications require self-organizing, wireless networks that can operate in dynamic environments and provide peer-to-peer, multi-hop, multi-media communications. Key to this technology is the ability of neighboring nodes to transmit without interference. Neighboring nodes transmit without interference by choosing time slots and channels that do not cause collisions at the intended unicast or multicast receivers. This functionality is provided by the Unifying Slot Assignment Protocol (USAP) which is disclosed in U.S. Pat. No. 5,719,868 and which is herein incorporated by reference. The function of USAP is to monitor the RF environment and allocate the channel resources on demand and automatically detect and resolve contention resulting from changes in connectivity.
One of the many tradeoffs that designers of such networks must make is maximizing network size and density in the face of limited channel resources. The challenge is to find methodologies which maintain the desirable network characteristics while providing organization of nodes with respect to densely and sparsely populated portions of the network. These methodologies typically require significant overhead, including computational costs or large storage and transmission requirements.
Thus, there is a need and desire for a heuristic procedure that uses minimal overhead to implement the channel resource allocation to establish a broadcast channel for datagram and control traffic and point-to-point links for higher throughput or delay sensitive traffic. Further, there is a need and desire for a heuristic method that uses a very small packet transmitted on a common channel that both initializes the network and contains slot allocations for network operations. Further still, there is a need and desire for a heuristic technique that separates nodes in densely populated areas into logical neighborhoods that, although managed separately, can be bridged for sharing critical network information and user traffic.
The present invention relates to a method for automatically managing the communication channel resources between two nodes having neighboring nodes in a network of transceiver nodes. Each node communicates during specific time slots and uses multiple frequencies on a time multiplex basis. The method includes storing possible communication time slots and frequencies between nodes in the network at each node. The method further includes announcing and transmitting from a first node during a specific time slot, a specific transmit slot and frequency and the identification of a second node to all neighboring nodes of the first node comprising a first set of neighboring nodes. The method still further includes transmitting from the first node a control packet containing transmit and receive information of the first node and the first set of neighboring nodes and identifying the announced selected transmit slot and frequency in the first set of neighboring nodes. The announced selected transmit slot and frequency is used to establish substantially contention free communication on the selected transmit slot and frequency between the first and second nodes. Further still, the method includes adapting to the transceiver node network density by utilizing logical neighborhooding.
The present invention relates to a communication network including a network of transceiver nodes, each node having neighbors, utilizing a time division multiple access structure the time division multiple access structure has bootstrap slots, broadcast slots, and traffic slots. Each node includes a boot manager having a logical neighborhooding protocol. Each node also includes a slot assignment protocol that chooses the number of slots to assign to each neighboring node and coordinates the activation of the slots for the neighboring nodes. Each node further includes a slot allocation storage, communicating with the slot assignment protocol, and a channel access communicating with the boot manager.
The present invention still further relates to a method of automatically managing the communication channel resources between two nodes having neighboring nodes in a network of transceiver nodes, wherein each node communicates during specific time slots and uses multiple frequencies on a time multiplex basis. The method includes storing possible communication time slots and frequencies between nodes in the network of each node. The method further includes announcing and transmitting from a first node during a specific time slot, a specific transmit slot and frequency and the identification of a second node to all neighboring nodes of the first node comprising a first set of neighboring nodes. The method still further includes transmitting from the first node a control packet containing transmit and receive information of the first node and the first set of neighboring nodes. The method still further includes and identifying the announced selected transmit slot and frequency in the first set of neighboring nodes and adapting to the transceiver node network density by creating logical neighborhoods over a plurality of frequencies when the network density exceeds a predetermined limit.